Re: [p2pi] One more proposed definition of fairness...

[Joe Touch <[e-mail]>]

Nicholas Weaver wrote:
> 
> On Jun 8, 2008, at 10:39 AM, Joe Touch wrote:
>> Nicholas Weaver wrote:
>>> (Buried in a previous mail, but I'd like comments on this separately)
>>> How does the following sound as one possible ideal goal for user- 
>>> fairness:
>>> "Mechanisms to enable the network to enforce traffic such that, in 
>>> the  presence of congestion, a user's congestion control response 
>>> becomes  equivalent to aggregating all traffic from that user into a 
>>> single TCP  stream."
>>
>> See the Congestion Manager or RFC2140 ;-)
>>
>> This is easy to do at the end system, but, AFAICT, impossible to 
>> accomplish anywhere else (users will just grab multiple IP addresses, 
>> e.g.) - or worse, involves violating TCP (or, equivalently, won't work 
>> on encrypted/authenticated streams).
> 
> 
> I'm a security person.  I have to assume the end systems don't behave 
> right.  But I actually don't think it is impossible to enforce in the 
> network for the local users' ISP.
...
> EG, the ISP can at a single bidirectional point in the network 
> (admittedly keeping lots of state, but...) for a large group of users 
> infer the congestion on each TCP flow,...

That's the point, however, where things stop when someone uses encrypted 
transport layers.

...
> Yes, this is a LOT of engineering work to get right [1], but I believe 
> it is doable, and could accomplish the stated definition of fairness (or 
> something very close to it).

A key question is whether it's worth the state it will take to get 
right. An endpoint might open a few thousand flows just to help overload 
your system ;-)

> Furthermore, you can resist the attacks you mentioned.  Because the ISP 
> can prevent the user from minting new IP addresses (as they control the 
> point of attachment), this prevents address forging.

Sure - the local ISP can prevent that. You can't prevent someone 
accessing multiple ISPs (cable, DSL, etc.), but presumably you don't 
care about that?

Joe

_______________________________________________
p2pi mailing list
[e-mail]
https://www.ietf.org/mailman/listinfo/p2pi